1. Field of the Invention
The present invention relates to a quantum dot, and more specifically, to a microcapsular quantum dot-polymer composite.
2. Discussion of Related Art
Since a quantum dot is a semiconductor particle having a core or core-shell structure which is a few nanometers in size, and quantum dots emit light in various wavelength ranges through energy obtained from excitation according to a size of the particle, it is effectively used for applications, especially, in the field of LED lighting. For applications of the quantum dot in the field of LEDs, the quantum dot is typically dispersed in a resin solution for use.
However, it has been known that the quantum dots have low dispersibility due to a strong aggregation tendency of the particles, and thus, quantum efficiency decreases. Further, quantum efficiency also decreases due to a physicochemical conversion of the quantum dots when the quantum dots are exposed to an oxidizing environment such as oxygen or moisture, or under a high temperature condition. In order to reduce aggregation of the quantum dots, there have been attempts to prevent aggregation of the quantum dots to increase stability of the quantum dot by covalent bonding with ligands such as tri-n-octylphosphine oxide (TOPO), oleic acid, stearic acid, palmitic acid, octadecylamine, hexadecylamine, or the like on the surface of the quantum dot (refer to U.S. Pat. No. 7,056,471, etc.). However, when the quantum dots are dispersed in a curable resin solution, aggregation of the quantum dots may occur, or quantum efficiency may decrease, and quantum efficiency may continuously decrease after curing resins.
Further, according to the result of an accelerated life test, which is a test method of measuring long term stability of the quantum dots in the curable resin necessary for practical use of the quantum dots in applications for LED, or the like, it has been known that quantum efficiency rapidly decreases according to processing time. Consequently, a commercial application of the quantum dots is limited.